class Cat(object):
    def say(self):
        print('I am a cat')


class Dog(object):
    def say(self):
        print('I am a dog')
        

class Duck(object):
    def say(self):
        print('I am a duck')


animal_list = [Cat, Dog, Duck]
for an in animal_list:
    an().say()

a = ['bobby1', 'bobby2']
b = ['bobby2', 'bobby']
name_tuple = ['bobby3', 'bobby4']
name_set = set()
name_set.add('bobby5')
name_set.add('bobby6')
a.extend(name_set)
print(a)
